Biomechanics of ankle joint during landing in counter movement jump and straddle jump

Ankle sprain is one of the most common sport injuries during landing of counter movement jump and straddle jump in baseball and volleyball exercise. Ankle sprain patients will lead to ankle functional instability. Most of functional instability patients occurs recurrent ankle sprain. The purpose of this study are estimate the ankle joint kinetics and ground impact pattern during landing in counter movement jump and straddle jump. The comparison between functional instability group and control group were also evaluated. The result showed that the injury risk in straddle jump is much higher than that in counter movement jump because of the shorter time to reach higher peak force in straddle jump. Also, the injury risk in functional instability group is higher than control group because of high impulses during landing.